There have been many different prior art patents relating to so-called wire twisting pliers, and several of these patents have addressed the question of reversible twisting or twisting in opposite directions, i.e., having the pliers capable of twisting either in a clockwise or counterclockwise direction.
One particular reversible type wire twisting plier is shown and described in U.S. Pat. No. 4,665,953 to Randall. This plier utilizes a conventional "yankee" mechanism mounted on one of the handles of a plier device, and incorporates the conventional "yankee" type flat sliding switch to reverse directions. This plier also incorporates an automatic locking feature wherein when the plier handles are squeezed to a closed position, the pliers automatically lock in this closed or gripping position and require digital intervention to allow for the opening of the pliers. This particular prior art device has several drawbacks. One drawback is the relative difficulty in accessing the reversing slide to reverse the direction of twisting and the absence of any readily visible or apparent indicia to indicate for which direction of rotation the pliers are set. Further, the locking feature on this plier automatically locks the pliers each time the handles are squeezed to close the jaws; and thus, every time the pliers are used whether or not for twisting, the pliers will lock in the closed position and require digital intervention for unlocking. This is time consuming especially in situations where a relatively minor portion of the use of the pliers is for twisting thus requiring positive unlocking every time the pliers are used.
Other devices which incorporate types of twisting include U.S. Pat. No. 2,737,983 to Prey. This patent also provides for twisting in a clockwise or counterclockwise direction but again utilizes a slide button for reversing.
Other types of rotating mechanisms are shown in U.S. Pat. No. 1,436,637 to Bates, U.S. Pat. No. 2,300,392 to Austin, U.S. Pat. No. 2,521,816 to Adams and U.S. Pat. No. 2,481,633 to Wehner. None of these patents show an actuator mechanism for reversing the direction and a locking mechanism which will not automatically lock upon closure.
U.S. Pat. No. 5,211,209, assigned to the assignee of the present invention, discloses a reversible plier type tool, wherein the direction is reversed by a mechanism which is axially slidable on the tube sleeve housing the rotary mechanism. This is a substantial improvement over the prior art tools. However, the axially movable sliding mechanism is prone to be inadvertently changed by the operator unintentionally moving the slide during manipulation of the tool thus changing the rotational direction of the operation of the tool.